Resin composition and multilayer structure using same

ABSTRACT

A method of making a resin composition comprising; a polyolefin (A); a saponified ethylene-vinyl acetate copolymer (EVOH) (B) having an ethylene content of 20-65 mol % and a degree of saponification of 96% or more; a higher fatty acid metal salt (C) having 8 to 22 carbon atoms; a conjugated polyene compound (D) having a boiling point of 20° C. or higher; an ethylene-vinyl acetate copolymer (E); and a saponified ethylene-vinyl acetate copolymer (F) having an ethylene content of 68-98 mol % and a degree of saponification of 20% or more, wherein the mass ratio (A:B) is 60:40 to 99.9:0.1, the amount of the higher fatty acid metal salts (C) is in the range of 0.0001 to 10 pbm per 100 pbm of the total of the polyolefin (A) and the EVOH (B), the amount of conjugated polyene compound (D) is in the range of 0.000001 to 1 pbm, and the total amount of the ethylene-vinyl acetate copolymer (B) and the saponified ethylene-vinyl acetate copolymer (F) is 0.3 pbm or more.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. Ser. No. 12/991,757,filed on Nov. 9, 2010, which is a National Stage (371) ofPCT/JP10/055594, filed on Mar. 29, 2010, and claims priority to JP2009-089133, filed Apr. 1, 2009.

TECHNICAL FIELD

The present invention relates to a resin composition comprising apolyolefin, and a saponified ethylene-vinyl acetate copolymer (may beabbreviated as EVOH hereinafter) which is improved in preventing theformation of film surface anomalies arising from insufficient dispersionof EVOH at the time of melt molding the resin compositions, morespecifically to a resin composition which is improved in formation ofEVOH aggregates at a micro-scale level and formation of wavy patterns onthe surface of molded articles; and relates also to a multilayerstructure including a layer comprising such a resin composition.

BACKGROUND ART

Resin compositions made by blending polyolefins and EVOH are well known(see Patent Document 1). However, these resin compositions are generallypoor in compatibility with each other and, hence, when formed into film,sheet, bottle or the like by extrusion molding, the compositions tend togenerate nonuniform phase-separated foreign matters. The number of theforeign matters increases particularly during long periods of operationand the appearance of the molded articles is significantly impaired(reduction of long-run processability). Additional problems, such asformation of lip stain around the die exit at the time of the extrusionprocess of the resin compositions, are also known. This lip stain canbecome mixed in the molded articles, lowering their quality.

It is known that blending higher fatty acid metal salts having 8 to 22carbon atoms, ethylenediaminetetraacetate metal salts, and/or such ashydrotalcite compounds is effective in improving the insufficientcompatibility between polyolefin and EVOH (see Patent Documents 1 and2). In addition to the combination, it is disclosed that, in addition toblending hydrotalcite based compounds and higher fatty acid metal saltshaving 8 carbon atoms or more in the mixture of a polyolefin and anEVOH, the addition of boron compounds, phosphoric acids and/or alkali(alkali-earth) hydrogen phosphates, or lower fatty acid metal saltshaving 7 carbon atoms or less, or the like, improves long-runprocessability and heat resistance of compositions mainly comprising apolyolefin and an EVOH at the time of melt molding (physical propertyretention at repeated heating accompanying recycling) (see PatentDocuments 3, 4 and 5). In these documents, however, the evaluation offish-eye formation at the time of film molding is done by observing thenumber of fish-eye particles having a diameter of 0.2 mm or more formedper 100 cm².

It is also disclosed that saponified ethylene-vinyl acetate copolymershaving an ethylene content of 68 to 98 mol % and having a degree ofsaponification of vinyl acetate units of 20% or more (may be abbreviatedas S-EVOH hereinafter) may be blended as resin compositions capable ofpreventing wavy pattern formation on the molded articles surface inaddition to using at least one component selected from higher fatty acidmetal salts having 8 to 22 carbon atoms, ethylenediaminetetraacetatemetal salts, and hydrotalcites described above to a polyolefin and anEVOH, at the time of melt-molding resin compositions comprising apolyolefin and an EVOH. The wavy patterns arise from flow anomalies dueto insufficient compatibility at the time of melt molding. In thismanner, the compatibility of the obtained resin compositions is improvedand the wavy patterns on the molded article surface are prevented, andthus the effective reuse of scrap compositions such as regrinds isdisclosed (see Patent Document 6).

It has also been disclosed that by adding an acid graft-modifiedpolyolefin based resin and a polyalcohol compound to recycled materialsof layered products including thermoplastic resin layers and EVOHlayers, the resin compositions showing no gelation at the time of meltmolding, producing no wavy patterns or fish-eyes on the molded articles,having an excellent long-run processability, and capable of preventingthe phase-separated foreign matter (lip stain), can be obtained (seePatent Document 7). However, in this document, evaluation of fish-eyeformation is done by observing the number of fish-eye particles having adiameter of 0.4 mm or more formed per 100 cm² in the regrind layer ofthe layered products.

In addition, a method for manufacturing vinyl acetate based polymers bythe addition of a conjugated polyene compound having a boiling point of20° C. or more to an ethylene-vinyl acetate copolymer, and a method formanufacturing saponified vinyl acetate based polymers by thesaponification of the vinyl acetate based polymers obtained in thismethod, have also been disclosed. EVOH obtained by these methods isconsidered of high quality showing minimal coloration and minimalformation of gel-like hard spots at the time of molding (see PatentDocument 8).

Also, resin compositions made by blending EVOH with an ethylene-vinylacetate copolymer having an ethylene content of 60 to 98 mol % andS-EVOH, and multilayer structures consisting of at least 2 layersincluding the resin composition layers, have been disclosed. Accordingto this reference, resin compositions having excellent gas barrierproperties and improved flexibility and transparency can be obtained(see Patent Document 9).

According to the arts disclosed in Patent Documents 2 to 7,compatibility between EVOH and polyolefin in the resin compositions madeby blending polyolefin and EVOH can be greatly improved, resulting inimproved appearance of the molded articles. However, in the currentenvironment-responsive trend (volume reduction of packaging materialsand waste materials), demand for thinning of cups, bottles and films ison the increase. Therefore, the need for reducing the poor appearancedue to insufficient dispersion at a more micro-scale level and flowanomalies of resin compositions made by blending polyolefin and EVOH isalso increasing. For traditional packaging materials, which wererelatively thick, there were no such problems because of the lowtransparency and the like. In Patent Document 8, the art of reducing thegel-like hard spots in molded articles made of EVOH alone is disclosed.In Patent Document 9, the art of improving the flexibility of moldedarticles made mainly of EVOH alone is disclosed. No mention or hint ofresin compositions made by blending EVOH and polyolefin is found inPatent Documents 8 and 9.

PRIOR ART DOCUMENTS Patent Document

[Patent Document 1]

Laid-open Japanese patent publication No. S60-199040

[Patent Document 2]

Laid-open Japanese patent publication No. H6-87195

[Patent Document 3]

Laid-open Japanese patent publication No. H10-001569

[Patent Document 4]

Laid-open Japanese patent publication No. H10-001570

[Patent Document 5]

Laid-open Japanese patent publication No. H09-278952

[Patent Document 6]

Laid-open Japanese patent publication No. H03-72542

[Patent Document 7]

Laid-open Japanese patent publication No. 2008-115367

[Patent Document 8]

Laid-open Japanese patent publication No. H09-71620

[Patent Document 9]

Laid-open Japanese patent publication No. H03-192140

SUMMARY OF INVENTION Problems to be Solved by the Invention

The present inventors have found that the film surface anomalies, whichappear at the time of melt molding the resin composition made byblending a polyolefin and an EVOH, and which impair the appearance, arecaused by insufficient dispersion of EVOH, or more specifically, theformation of EVOH aggregates at a micro-scale level.

Accordingly, the objects of the present invention are to improve thedispersibility of EVOH by suppressing the formation of aggregates at amicro-scale level, to reduce the occurrences of poor appearance such aswavy patterns on the molded article surface caused by flow anomalies dueto the aggregates, and thus to effectively reuse the layered productcomprising the polyolefin layer and the EVOH layer, or other such asscrap portion, as a regrind layer, and finally to obtain molded articleswith good appearance.

Means for Solving the Problem

According to the present invention, the above-described object can beachieved by providing a resin composition comprising: a polyolefin (A);a saponified ethylene-vinyl acetate copolymer (B) having an ethylenecontent of 20 to 65 mol % and having a degree of saponification of vinylacetate units of 96% or more (hereinafter simply, “EVOH (B)”); a higherfatty acid metal salt (C) having 8 to 22 carbon atoms (hereinaftersimply, “higher fatty acid metal salt (C)”); a conjugated polyenecompound (D) having a boiling point of 20° C. or higher (hereinaftersimply, “conjugated polyene compound (D)”); an ethylene-vinyl acetatecopolymer (E) (hereinafter, “EVAc (E)”); and a saponified ethylene-vinylacetate copolymer (F) having an ethylene content of 68 to 98 mol % andhaving a degree of saponification of vinyl acetate units of 20% or more(hereinafter, “S-EVOH (F)”), wherein the mass ratio (A:B) of thepolyolefin (A) and the EVOH (B) is 60:40 to 99.9:0.1, the amount ofhigher fatty acid metal salts (C) is in the range of 0.0001 to 10 partsby mass per 100 parts by mass of the total of polyolefin (A) and EVOH(B), the amount of conjugated polyene compound (D) is in the range of0.000001 to 1 part by mass per 100 parts by mass of the total ofpolyolefin (A) and EVOH (B), and the total amount of an EVAc (E) and theS-EVOH (F) is 0.3 part by mass or more per 100 parts by mass of thetotal of polyolefin (A) and EVOH (B).

In the resin composition, it is a preferable embodiment of the presentinvention that the mass ratio (E:F) between the ethylene-vinyl acetatecopolymer (E) and the saponified ethylene-vinyl acetate copolymer (F) isin the range of 99.9:0.1 to 70.0:30.0.

In the resin composition, preferably, a master batch is prepared inadvance by melt-blending the higher fatty acid metal salt (C) having 8to 22 carbon atoms, the ethylene-vinyl acetate copolymer (E), and thesaponified ethylene-vinyl acetate copolymer (F), and the resincomposition is obtained by melt-blending the master batch, thepolyolefin (A), the saponified ethylene-vinyl acetate copolymer (B), andthe conjugated polyene compound (D) having a boiling point of 20° C. orhigher.

Preferably, a master batch is prepared in advance by melt-blending thepolyolefin (A), the higher fatty acid metal salt (C), the EVAc (E), andthe S-EVOH (F), and the resin compositions are obtained by melt-blendingthe master batch, the polyolefin (A), the EVOH (B), and the conjugatedpolyene compound (D).

It is a preferable embodiment in the resin composition according to thepresent invention that the master batch (obtained above) analyzed bynuclear magnetic resonance spectroscopy (¹H-NMR) method shows a signalstrength ratio (Ja:Jb) between the signal Ja deriving from the hydrogenatoms bonded to the carbon atoms to which acetoxy groups are bonded, andthe signal Jb deriving from the hydrogen atoms bonded to the carbonatoms to which hydroxyl groups are bonded, in the range of 99.5:0.5 to70.0:30.0.

A resin composition obtained as follows is also a preferable embodimentof the present invention: a resin composition obtained by furthercontaining in the above resin composition a hydrotalcite (G) in therange of 0.0001 to 10 parts by mass per 100 parts by mass of the totalof the polyolefin (A) and the EVOH (B).

A preferable embodiment of the present invention also is a multilayerstructure having at least two layers comprising a layer made of any oneof the above-described resin compositions, and a layer made of asaponified ethylene-vinyl acetate copolymer having an ethylene contentof 20 to 65 mol % and having a degree of saponification of vinyl acetateunits of 96% or more.

Advantageous Effects of Invention

The present invention offers resin compositions capable of suppressingthe formation of EVOH aggregates at the micro-scale levels to improvethe dispersibility and reducing the occurrences of flow anomalies causedby the aggregates. The resin composition of the present invention can beused as a recycled regrind layer even from scraps, etc., of layeredproducts having the polyolefin layer and the EVOH layer. Even in thiscase, molded articles without defects in the appearance can be obtained.

DESCRIPTION OF EMBODIMENTS

The resin composition of the present invention contains polyolefin (A),EVOH (B), higher fatty acid metal salt (C), conjugated polyene compound(D), EVAc (E), and S-EVOH (F). The mass ratio of polyolefin (A) and EVOH(B), (A:B), is 60:40 to 99.9:0.1. The amount of higher fatty acid metalsalts (C) contained is in the range of 0.0001 to 10 parts by mass per100 parts by mass of the total of polyolefin (A) and EVOH (B). Theamount of conjugated polyene compound (D) is in the range of 0.000001 to1 part by mass per 100 parts by mass of the total of polyolefin (A) andEVOH (B). The total amount of EVAc (E) and S-EVOH (F) contained is 0.3part by mass or more per 100 parts by mass of the total of polyolefin(A) and EVOH (B).

Polyolefin (A) used in the present invention includes polyethylene (lowdensity, linear low density, medium density, and high density); ethylenebased copolymers prepared by copolymerization of ethylene and α-olefinssuch as 1-butene, 1-hexene and 4-methyl-1-pentene or acrylic esters;polypropylene (homo polypropylene, random polypropylene, blockpolypropylene, etc.); propylene based copolymers prepared bycopolymerization of propylene and α-olefins such as ethylene, 1-butene,1-hexene, 4-methyl-1-pentene; modified polypropylenes blended withrubber based polymers; poly(1-butene), poly(4-methyl-1-pentene),modified polypropylenes prepared by reacting the polyolefin with maleicanhydride; and ionomer resins. In the present invention, as polyolefins(A), it is preferable to use polypropylene based resins of polypropyleneor propylene based copolymers, or polyethylene based resins ofpolyethylene or ethylene based copolymers. In particular, it is morepreferable to use polypropylene based resins. As a polyolefin (A), onesingle polyolefin or two or more mixed polyolefins may be used. When,out of these polyolefins (A), polyolefins containing halogen compoundsfrom polymerization catalyst residues or existing as impurities inadditives such as fillers and pigments at a level of 1 to 300 ppm,preferably 3 to 150 ppm, in terms of halogens are used, the effect ofthe present invention will be more remarkable.

EVOH (B) used in the present invention is ethylene-vinyl acetatecopolymer with its vinyl acetate units saponified (hydrolyzed). EVOHhaving a relatively low ethylene content and a high degree ofsaponification (degree of hydrolysis) of vinyl acetate units tends toshow poor compatibility with polyolefin. If the ethylene content in EVOHis excessive, the gas barrier property of the resin compositionaccording to the present invention will be reduced. If the degree ofsaponification (degree of hydrolysis) of the vinyl acetate units in EVOHis low, the thermal stability of the EVOH itself will be poor. Fromthese standpoints, the ethylene content of EVOH (B) according to thepresent invention is 20 to 65 mol %, or preferably 20 to 60 mol %, andmore preferably 20 to 50 mol %. The degree of saponification of vinylacetate units of EVOH (B) is preferably 96% or more, or more preferably98% or more, and even more preferably 99% or more. EVOH having anethylene content of 20 to 65 mol % and a degree of saponification of 99%or more is especially important as a subject matter to which the presentinvention applies because it can be used to obtain containers havingexcellent properties such as gas barrier property when laminated withpolyolefin (A).

The EVOH (B) may be modified with other copolymerizable monomers to theextent that does not inhibit the effect of the present invention,usually in the range of not more than 5 mol %. Examples of the modifyingcopolymerizable monomer include α-olefins such as propylene, 1-butene,1-hexene, and 4-methyl-1-pentene; esters such as acrylic acid esters andmethacrylic acid esters; higher fatty acids such as maleic acid, fumaricacid, and itaconic acid, and vinyl esters thereof; alkyl vinyl ethers;N-(2-dimethylaminoethyl) methacrylamide or its quaternary compounds,N-vinylimidazole or its quaternary compounds, N-vinylpyrrolidone,N,N-butoxymethylacrylamide, vinyltrimethoxysilane,vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, and the like.

It is desirable that the melt index (MI; measured at 190° C., under aload of 2160 g) of EVOH (B) is 0.1 g/10 minutes or more, or preferably0.5 g/10 minutes or more, and 100 g/10 minutes or less, or morepreferably 50 g/10 minutes or less, and most preferably 30 g/10 minutesor less. In this case, from the viewpoint of the dispersibility of EVOH(B), the ratio of MI (B)/MI (A) is preferably in the range of 0.1 to100, and more preferably 0.3 to 50. Here, MI (B) is MI of EVOH (B) andMI (A) is MI of polyolefin (A) (measured at 190° C., under a load of2160 g).

To realize the best effect of the present invention, it is important tokeep the mass ratio (A:B) of the polyolefin (A) and the EVOH (B) in theresin composition according to the present invention in the range of60:40 to 99.9:0.1. In the mass ratio, if EVOH (B) exists at a higherlevel than 60:40, the effect of preventing the aggregation of EVOH (B)at a micro-scale level cannot be fully realized. If polyolefin (A)exists at a higher level than 99.9:0.1, the effect of the presentinvention cannot be fully observed. From this viewpoint, it is morepreferable to keep the mass ratio (A:B) of polyolefin (A) and EVOH (B)in the range of 65:35 to 99.7:0.3.

As for higher fatty acid metal salts (C) according to the presentinvention, metal salts of lauric acid, stearic acid, myristic acid andthe like can be used. As for the metal salts, those of Group I, II, orIII of the periodic table, for example, such as sodium salt, potassiumsalt, calcium salt, and magnesium salt, can be listed. Zinc salt ofthese fatty acids may also be used. Of these, the metal salts of GroupII of the periodic table, such as calcium salt and magnesium salt, arepreferable as they can produce the effect of the present invention whenadded in a small quantity.

If the amount of higher fatty acid metal salts (C) to be added is toosmall, the effect of the present invention cannot be realized. If anexcessive amount of the salts is added, it may promote thermaldegradation of EVOH (B) and cause foaming by decomposition gases, orcoloration. For this reason, it is preferable that the amount of higherfatty acid metal salts (C) to be added is in the range of 0.0001 to 10parts by mass per 100 parts by mass of the total of polyolefin (A) andEVOH (B), or more preferable in the range of 0.001 to 1 part by mass.

Conjugated polyene compounds (D) used in the present invent ion arecompounds having so-called conjugating double bonds and have a structurein which carbon-carbon double bonds and carbon-carbon single bonds areconnected alternately, with the number of carbon-carbon double bondsbeing 2 or more. A conjugated polyene compound (D) may be a conjugateddiene having 2 carbon-carbon double bonds and 1 carbon-carbon singlebond connected alternately, or a conjugated triene having 3carbon-carbon double bonds and 2 carbon-carbon single bonds connectedalternately. It may be a conjugated polyene compound having a greaternumber of carbon-carbon double bonds and carbon-carbon single bondsconnected alternately. Polyenes having fewer than 7 carbon-carbon doublebonds to conjugate are preferred as, if the number of carbon-carbondouble bonds to conjugate is 8 or more, the conjugated polyene compoundmay color the molded articles by its own color. Also, the polyene maycontain, in one molecule, a plurality of independent sets of conjugatingdouble bonds each consisting of 2 or more carbon-carbon double bonds.For example, a compound such as wood oil that has 3 conjugated trienesin one molecule can be included in conjugated polyene compounds (D).Conjugated polyene compounds (D) may also contain, in addition toconjugating double bonds, other functional groups. These functionalgroups include carboxylic group and its salt, hydroxyl group, estergroup, carbonyl group, ether group, amino group, imino group, amidegroup, cyano group, diazo group, nitro group, sulfonic group, sulfoxidegroup, sulfide group, thiol group, sulfonic acid group and its salt,phosphate group and its salt, phenyl group, halogen atom, double bond,and triple bond.

Specific examples of conjugated polyene compounds (D) include conjugateddiene compounds having conjugation structures of 2 carbon-carbon doublebonds such as: isoprene; 2,3-dimethyl-1,3-butadiene;2,3-diethyl-1,3-butadiene; 2-t-butyl-1,3-butadiene; 1,3-pentadiene;2,3-dimethyl-1,3-pentadiene; 2,4-dimethyl-1,3-pentadiene;3,4-dimethyl-1,3-pentadiene; 3-ethyl-1,3-pentadiene;2-methyl-1,3-pentadiene; 3-methyl-1,3-pentadiene;4-methyl-1,3-pentadiene; 1,3-hexadiene; 2,4-hexadiene;2,5-dimethyl-2,4-hexadiene; 1,3-octadiene; 1,3-cyclopentadiene;1,3-cyclohexadiene; 1-phenyl-1,3-butadiene; 1,4-diphenyl-1,3-butadiene;1-methoxy-1,3-butadiene; 2-methoxy-1,3-butadiene;1-ethoxy-1,3-butadiene; 2-ethoxy-1,3-butadiene; 2-nitro-1,3-butadiene;chloroprene; 1-chloro-1,3-butadiene; 1-bromo-1,3-butadiene;2-bromo-1,3-butadiene; fulvene; tropone; ocimene; phellandrene; myrcene;farnesene; cembrene; sorbic acid; sorbic acid ester; sorbic acid salt;and abietic acid; conjugated triene compounds having conjugationstructures of 3 carbon-carbon double bonds such as: 1,3,5-hexatriene;2,4,6-octatriene-1-carboxylic acid; eleostearic acid; wood oil; andcholecarciferol; and conjugated polyene compounds having conjugationstructures of 4 or more carbon-carbon double bonds such as:cyclooctatetraene; 2,4,6,8-decatetraene-1-carboxylic acid; retinol; andretinoic acid. These conjugated polyene compounds (D) may be usedsingularly or in combinations of 2 or more compounds.

The amount of conjugated polyene compounds (D) to be added is in therange of 0.000001 to 1 part by mass per 100 parts by mass of the totalof polyolefin (A) and EVOH (B), or more preferably in the range of0.00001 to 1 part by mass. If the added amount is less than 0.00001 partby mass per 100 parts by mass of the total of polyolefin (A) and EVOH(B), the effect of the present invention may not be satisfactory. If theadded amount is greater than 1 part by mass per 100 parts by mass of thetotal of polyolefin (A) and EVOH (B), gelation of the obtained resincompositions may be promoted.

Conjugated polyene compound (D) may be directly blended in the mixtureof polyolefin (A) and EVOH (B). If the added amount is very small, itmay be blended in EVOH (B) with good compatibility in advance so that itcan be uniformly dispersed in the resin composition of the presentinvention.

EVAc (E) used in the present invention may be random copolymers preparedby polymerizing ethylene and vinyl acetate according to known methods,terpolymer prepared by copolymerizing another monomer, or modified EVAcmodified by grafting. The vinyl acetate unit content of EVAc (E) ispreferably 2 to 40 mol %, or more preferably 5 to 25 mol %. If the vinylacetate unit content is below 2 mol % or above 40 mol %, EVOH (B)aggregation may not be effectively prevented. The melt index (MI;measured at 190° C., under a load of 2160 g) of EVAc (E) is preferablyin the range of 0.1 to 50 g/10 minutes, or more preferably 0.5 to 30g/10 minutes, and even more preferably 1 to 20 g/10 minutes.

S-EVOH (F) used in the present invention is a saponified ethylene-vinylacetate copolymer having an ethylene content of 68 to 98 mol % andhaving a degree of saponification of vinyl acetate units of 20% or more.Unlike the usual type of EVOH used for food wrapping materials, it hashigh ethylene content and is capable of significantly improvingcompatibility between polyolefin (A) and EVOH (B). The ethylene contentof S-EVOH (F) is preferably 70 mol % or more, and it is preferably 96mol % or less, or more preferably 94 mol % or less. The degree ofsaponification of vinyl acetate units is preferably 30% or more, or morepreferably 40% or more. The upper limit of the degree of saponificationis not strictly defined. Materials with a degree of saponification of 99mol % or more or substantially 100% can also be used. If the ethylenecontent is below 68 mol % or above 98 mol %, or if the degree ofsaponification of vinyl acetate units is less than 20%, the effect ofthe present invention will not be fully realized.

According to the specification of the present invention, the ethylenecontent of S-EVOH (F) should be higher than that of EVOH (B). Thedifference in the ethylene content between S-EVOH (F) and EVOH (B) ispreferably at least 10 mol % or more, and more preferably 20 mol % ormore from the standpoint of improving the compatibility betweenpolyolefin (A) and EVOH (B).

MI of S-EVOH (F) (measured at 190° C., under a load of 2160 g) ispreferably 0.1 g/10 minutes or more, more preferably 0.5 g/10 minutes ormore, and even more preferably 1 g/10 minutes or more. At the same time,the MI of S-EVOH (F) is preferably 100 g/10 minutes or less, or morepreferably 50 g/10 minutes or less, and even more preferably 30 g/10minutes or less. S-EVOH (F) used in the present invention may bemodified with an unsaturated carboxylic acid or its derivatives. Theseunsaturated carboxylic acids or derivatives include acrylic acid,methacrylic acid, maleic acid, fumaric acid, itaconic acid, and maleicacid; methyl or ethyl esters of these acids; and maleic anhydride,itaconic anhydride, and the like. These acid monomers may be usedsingularly or in combination.

The total amount of EVAc (E) and S-EVOH (F) added to the resincomposition of the present invention is 0.3 part by mass or more per 100parts by mass of the total of polyolefin (A) and EVOH (B), and ispreferably 0.5 part by mass or more. If the addition is less than 0.3part by mass, the effect of EVAc (E) and S-EVOH (F) addition will not befully realized. Although the upper limit of the addition is not clearlyspecified, excessive addition will not increase the dispersibility ofEVOH (B) in the resin composition above a certain limit. In a normalpractice, addition of 30 parts by mass or less will be sufficient.

In the resin composition of the present invention, the content of EVAc(E) and S-EVOH (F) in terms of mass ratio (E:F) is preferably in therange of 99.9:0.1 to 70.0:30.0, and more preferably in the range of99.5:0.5 to 85.0:15.0. In this ratio, if the ratio of S-EVOH (F) isbelow those ranges, the dispersibility of EVOH (B) in the resincomposition may deteriorate and reduce the effects of the presentinvention. If the proportion of S-EVOH (F) is above those ranges, theeffect of improving the dispersibility of EVOH (B) will be lowered.

In addition to above-mentioned polyolefin (A), EVOH (B), higher fattyacid metal salts (C), conjugated polyene compounds (D), EVAc (E) andS-EVOH (F) that constitute the resin composition of the presentinvention, hydrotalcite (G) may be added. Addition of hydrotalcite (G)as a constituent of the resin composition of the present invention ispreferred because it improves the dispersibility of EVOH (B) in theresin compositions.

As hydrotalcite compounds (G) employed in the present invention,hydrotalcite complex salts shown by the following formula can be listed.M_(x)Al_(y)(OH)_(2x+3y−2z)(A)_(z) .aH₂O(where: M is one or more selected from Mg, Ca, Sr, Ba, Zn, Cd, Pb, Sn; Ais CO₃ or HPO₄; x, y, z are positive numbers; a is either 0 or apositive number: 2x+3y−2z>0).

In the hydrotalcites, M is preferably Mg, Ca or Zn, and more preferablyis a combination of two or more of these metals. Examples ofparticularly favorable hydrotalcites are listed below.

-   Mg₆Al₂(OH)₁₆CO₃.4H₂O-   Mg₈Al₂(OH)₂₀CO₃.5H₂O-   Mg₅Al₂(OH)₁₄CO₃.4H₂O-   Mg₁₀Al₂(OH)₂₂(CO₃)₂.4H₂O-   Mg₆Al₂(OH)₁₆HPO₄.4H₂O-   Ca₆Al₂(OH)₁₆CO₃.4H₂O-   Zn₈Al₂(OH)₁₆CO₃.4H₂O-   Mg₃ZnAl₂(OH)₁₂CO₃.2.7H₂O-   Mg₆ZnAl₂(OH)₂₀CO₃.1.6H₂O-   Mg₅Zn_(1.7)Al_(3.3)(OH)₂₀ (CO₃)_(1.65).4.5H₂O

When hydrotalcite (G) is further added, the added amount is in the rangeof 0.0001 to 10 parts by mass per 100 parts by mass of the total ofpolyolefin (A) and EVOH (B), and more preferably in the range of 0.001to 1 part by mass. If the added amount is less than 0.0001 part by massper 100 parts by mass of the total of polyolefin (A) and EVOH (B), theeffect of the present invention may not be satisfactory. If the addedamount is more than 10 parts by mass per 100 parts by mass of the totalof polyolefin (A) and EVOH (B), it may promote thermal degradation ofEVOH in the obtained resin composition and cause foaming bydecomposition gases, or coloration.

Adding modified polyolefin resins modified with unsaturated carboxylicacids or derivatives thereof to the resin composition of the presentinvention is effective in suppressing the aggregation of EVOH (B) at amicro-scale level. Here, modified polyolefin resins are polyolefinresins modified with one or more of unsaturated carboxylic acids orderivatives thereof, selected from the following groups: unsaturatedcarboxylic acids such as acrylic acid, methacrylic acid, maleic acid,fumaric acid, crotonic acid, itaconic acid and citraconic acid,including their esters or anhydrides; and derivatives of unsaturatedcarboxylic acids such as methyl acrylate, methyl methacrylate, ethylacrylate, propyl acrylate, butyl acrylate, butyl methacrylate, vinylacetate, glycidyl acrylate, glycidyl methacrylate, acrylamide,methacrylamide, sodium acrylate, and sodium methacrylate. As polyolefinresins before modification, polyethylene, polypropylene, ethylene-vinylacetate copolymer, and ethylene-acrylate ester copolymers can bepreferably listed.

Further, publicly known additives capable of improving variousproperties such as thermal stability at the time of melt extrusionmolding of EVOH may be preferably added within the reasonable extentthat does not inhibit the effect of the present invention as theseadditives may be expected to reduce the deterioration of EVOH (B) whichis a constituent of the resin composition of the present invention.These additives include organic acids such as acetic acid and lacticacid, inorganic acids such as hydrochloric acid and phosphoric acid,metal salts of these acids with metals of periodic table Groups I, IIand III, boron compounds such as boric acid, and higher fatty acids suchas stearic acid. In particular, addition of boric acid is effective tosuppress aggregation of EVOH (B), with the preferable amount to be addedranging from 0.0001 to 0.1 part by mass per 100 parts by mass of thetotal of polyolefin (A) and EVOH (B). Conversely, boric acid added inexcess of 0.1 part by mass per 100 parts by mass of the total ofpolyolefin (A) and EVOH (B) may promote the aggregation of EVOH (B).

In the following, the method of obtaining the resin composition of thepresent invention by mixing the polyolefin (A), EVOH (B), higher fattyacid metal salts (C), conjugated polyene compounds (D), EVAc (E), andS-EVOH (F), and the method of molding the resin compositions, will beexplained.

There are no particular restrictions with respect to methods forblending to obtain the resin composition according to the presentinvention. A method wherein polyolefin (A), EVOH (B), higher fatty acidmetal salts (C), conjugated polyene compounds (D), EVAc (E) and S-EVOH(F) are dry-blended together and then melt-blended; and a method whereinhigher fatty acid metal salts (C) and/or conjugated polyene compounds(D) are blended in advance in polyolefin (A) and/or EVOH (B), and themixture is dry-blended with the remaining components and thenmelt-blended; can be listed as examples. A preferable method is the onewherein a mixture prepared by blending polyolefin (A) and conjugatedpolyene compounds (D) in EVOH (B) is dry-blended with a mixture preparedby blending higher fatty acid metal salts (C), EVAc (E), and S-EVOH (F),and the final mixture is melt-blended. Another preferable method is theone wherein a mixture prepared by blending polyolefin (A) and conjugatedpolyene compounds (D) with EVOH (B) is dry-blended with another mixtureprepared by blending higher fatty acid metal salts (C), EVAc (E), andS-EVOH (F) with polyolefin (A), and then melt-blended.

As described above, when a conjugated polyene compound (D) is blended inEVOH (B) in advance, satisfactory results can be obtained as to theeffect of the present invention even when a reduced amount of conjugatedpolyene compound (D) is added. Methods of blending conjugated polyenecompound (D) in EVOH (B) in advance are not specified. A method islisted as an example wherein EVOH (B) is dissolved in a good solvent ofEVOH (B) such as water/methanol mixed solvent, and a conjugated polyenecompound (D) is dissolved in this solution at a concentration level of0.000001 to 10 parts by mass per 100 parts by mass of EVOH (B). Themixed solution is extruded into a poor solvent through a nozzle, etc.The deposit is precipitated, solidified, rinsed and dried to obtain EVOH(B) blended with a conjugated polyene compound (D).

Methods for blending a higher fatty acid metal salt (C), EVAc (E) andS-EVOH (F) in advance, and those for blending a higher fatty acid metalsalt (C), EVAc (E), and S-EVOH (F) in a polyolefin (A) in advance arenot specified. A method in which each component is dry-blended, or amethod in which each component is melt-blended and then pelletized so asto prepare a master batch, are listed as examples. Of these methods, thelatter is more favorable to easy handling from the standpoint thathigher fatty acid metal salts (C) are usually in a powder form.

When a sample of the master batch is analyzed by the nuclear magneticresonance spectroscopy (¹H-NMR) method, the signal strength ratio(Ja:Jb) is preferably in the range of 99.5:0.5 to 70.0:30.0. Here, Ja isthe signal deriving from the hydrogen atoms bonded to the carbon atomsto which acetoxy groups are bonded, and Jb is the signal deriving fromthe hydrogen atoms bonded to the carbon atoms to which hydroxyl groupsare bonded. In other words, it is preferable, from the standpoint ofimproving the dispersibility of EVOH (B), that carbon atoms bonded withacetoxy groups and carbon atoms bonded with hydroxyl groups exist in theresin composition of the present invention, and its existing molar ratiois in the range of 99.5:0.5 to 70.0:30.0. If the strength ratio iseither below 0.5 or above 30.0, the effect of improving thedispersibility of EVOH (B) may not be satisfactory.

As methods for keeping the strength ratio of Ja and Jb, i.e., (Ja:Jb),in the range of 99.5:0.5 to 70.0:30.0, a method of adjusting the mixingratio of EVAc (E) and S-EVOH (F) suitably, a method of adjusting thedegree of saponification of S-EVOH (F), and a method of adjusting theethylene content of EVAc (E) and/or S-EVOH (F) suitably, can be listed.

There are no particular restrictions with respect to methods forblending when adding hydrotalcite (G). A mixture of polyolefin (A), EVOH(B), higher fatty acid metal salts (C), conjugated polyene compounds(D), EVAc (E), and S-EVOH (F) can be dry-blended with hydrotalcite (G)and then melt-blended. If polyolefin (A), higher fatty acid metal salts(C), EVAc (E), and S-EVOH (F) are melt-blended and then pelletized inadvance to obtain a master batch, hydrotalcite (G) can be blended at thesame time to be included in the pellet when the master batch ismanufactured. This treatment is preferable from the standpoint ofreducing the number of materials to be handled at the final step ofmelt-blending the resin composition of the present invention.

The resin composition of the present invention may further blendadditives other than those described above to the extent that does notinhibit the effect of the present invention. These additives includeantioxidants, ultraviolet absorbers, plasticizers, antistatic agents,lubricants, coloring agents, fillers and other polymeric compounds.Specific examples of additives are shown below.

Antioxidants: 2,5-di-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol,4,4′-thiobis-(6-t-butylphenol),2,2′-methylene-bis-(4-methyl-6-t-butylphenol),octadecyl-3-(3′,5′-di-t-butyl-4′-hydroxylphenyl) propionate,4,4′-thiobis-(6-t-butylphenol), and the like.

Ultraviolet absorbers: ethylene-2-cyano-3,3′-diphenyl acrylate,2-(2′-hydroxyl-5′-methylphenyl)benzotriazole,2-(2′-hydroxyl-3′-t-butyl-5′-methylphenyl)-5-chlorobenzotriazole,2-hydroxyl-4-methoxybenzophenone, 2,2′-dihydroxyl-4-methoxybenzophenone,2-hydroxyl-4-octoxybenzophenone, and the like.

Plasticizers: dimethyl phthalate, diethyl phthalate, dioctyl phthalate,wax, liquid paraffin, phosphoric acid esters, and the like.

Antistatic agents: pentaerythrit monostearate, sorbitan monopalmitate,sulfated polyolefins, polyethylene oxide, carbowax, and the like.

Lubricants: ethylenebisstearoamide, butyl stearate, and the like.

Coloring agents: titanium oxide, carbon black, phthalocyanine,quinacrydone, indolin, azo pigments, colcothar, and the like.

Fillers: glass fiber, asbestos, balastonite, calcium silicate, and thelike.

Among these additives, coloring agents and fillers in particular, mayoften contain impurities that promote aggregation of EVOH (B) thatconstitutes the resin composition of the present invention at amicro-scale level. For this reason, when these additives are blended in,the amount of higher fatty acid metal salts (C) and/or conjugatedpolyene compounds (D), and/or EVAc (E) and/or S-EVOH (F) to be blendedmay have to be increased as needed.

Many other polymeric compounds may also be blended in the resincomposition of the present invention to the extent that does not inhibitthe effect of the present invention.

As the mixing tools for each constituent to obtain the resin compositionof the present invention, ribbon blenders, high-speed mixer-cokneaders,mixing rolls, extruders, intensive mixers, or the like, can be listed.

The resin composition of the present invention can be molded intodesired molded articles such as films, sheets, tubes, bottles, cups, andthe like through publicly known melt extrusion molding machines,compression molding machines, transfer molding machines, injectionmolding machines, blow molding machines, heat molding machines, rotarymolding machines, dipping molding machines, and the like. The extrusiontemperature for molding is generally in the range of 170 to 350° C.,although it is suitably selected depending on the type of polyolefin (A)constituting the resin composition of the present invention, meltindices of polyolefin (A) and EVOH (B), composition ratio of polyolefin(A) and EVOH (B), or type of molding machine and the like.

When the resin composition of the present invention is used as a layerconstruction of a multilayer structure containing the layer ofpolyolefin and the layer of EVOH, the multilayer structure may has anylayer construction with one or more layers positioned in arbitrarypositions. Such layer constructions are expressed as in the followinglayer constructions, where c is the resin composition of the presentinvention, a is polyolefin, b is EVOH, and ad is adhesive resin. Here,the modified polyolefin resin, modified with unsaturated carboxylicacids or derivatives thereof can be preferably used as ad.

3 layers: a/c/b

4 layers: c/b/ad/a, a/c/ad/b

5 layers: c/ad/b/ad/c, a/c/b/ad/a, a/c/b/c/a

6 layers: a/c/ad/b/ad/a

7 layers: a/c/ad/b/ad/c/a

In these multilayer structures, the resin composition of the presentinvention can be replaced with melt-blended scraps of the multilayerstructure. In addition to the multilayer structure, scraps of otherpolyolefin molding can be mixed and melt-blended. Therefore, in the casewhen an ad layer is used in such multilayer structures, the resincomposition of the present invention will necessarily contain ad as aconstituent.

As the multilayer structures of the layer construction contain EVOHhaving a high gas barrier property, these are useful as packagingmaterials for food products, medicinal products, and medical devices,and the like, which require high gas barrier properties.

As a method of multilayer formation, co-extrusion molding is a favorablemethod. In this method, a number of separate extruders corresponding tothe number of types of resin layers are used, and resins melted in eachextruder are simultaneously co-extruded to form a laminated layerstructure. Other applicable methods are multilayer formation methodsincluding extrusion coating and dry lamination, and the like. Further,molded articles having excellent mechanical properties and excellent gasbarrier properties can be obtained by performing the stretching on thesingular molded article of the resin composition of the presentinvention, or the multilayer structures containing the resin compositionof the present invention by means of monoaxial stretching, biaxialstretching, or blow stretching.

Molded articles obtained from the resin composition of the presentinvention have neat appearances and have excellent mechanical propertiesand excellent gas barrier properties, as EVOH in the resin compositionof the present invention is uniformly dispersed with its aggregation ata micro-scale level suppressed. Thus, these articles are of greatindustrial value.

EXAMPLES

In the following, the present invention will be explained in greaterdetail through examples. In the following manufacturing examples,examples, and comparative examples, “part” means “part by mass” unlessotherwise specified.

[Method of Quantitative Determination of Conjugated Polyene Compound (D)Blended in EVOH]

The amount of conjugated polyene compound (D) in EVOH was quantitativelydetermined in the following manner. In this method, EVOH containingconjugated polyene compound (D) was pulverized and sifted through a100-mesh sieve to eliminate coarse particles. A 10 g portion of thispowder was submitted to Soxhlet extraction for 48 hours with 100 ml ofchloroform. The amount of conjugated polyene compound in the extractionliquid was determined by high performance liquid chromatography usingcalibration curves prepared with the reference standard of eachconjugated polyene compound.

[NMR Analysis]

Various master batches containing EVAc (E) and S-EVOH (F), preparedaccording to the manufacturing examples described below, wereindividually dissolved in a mixed solvent ofo-dichlorobenzene/o-dichlorobenzene-d₄=80/20 (volume ratio) at aconcentration of 5 mass %. Measurement was performed with ¹H-NMR (500MHz, measurement temperature=120° C., accumulation number=1024 times,TMS, δ (ppm)). The signal strength ratio between Ja and Jb wascalculated by measuring the area ratios of signal Jb at around 3.58 ppm(deriving from hydrogen atoms bonded to the carbon atom to whichhydroxyl group is bonded), and signal Ja at around 5.05 ppm (derivingfrom hydrogen atoms bonded to the carbon atom to which acetoxy group isbonded).

Manufacturing Example 1

(1) 2000 parts of EVOH having an ethylene content of 32 mol %, having adegree of saponification of 99.8 mol %, and limiting viscosity [η]_(ph)of 0.092 l/g as measured at 30° C. using a liquid mixture ofwater/phenol=15/85 (mass ratio) as a solvent, were added to 18000 partsof a mixed solvent of water/methanol=40/60 (mass ratio) and completelydissolved by stirring for 6 hours at 60° C. To this solution, 2 parts ofsorbic acid were added as a conjugated polyene compound (D) andcompletely dissolved by stirring for 1 additional hour at 60° C. toobtain EVOH solution containing sorbic acid. This EVOH solution wascontinuously extruded into a coagulation bath of water/methanol=5/95(mass ratio) at 0° C. through a nozzle of 4 mm in diameter to coagulateEVOH in a stranded shape. This strand was then introduced into apelletizer to obtain porous EVOH chips.

(2) The porous EVOH chips obtained in (1) above were consecutivelyrinsed with 2000 parts of 0.1 mass % aqueous acetic acid solution andthen with 2000 parts of ion exchanged water at 20° C. followed byimmersion for 4 hours in 2000 parts of 0.092% aqueous boric acidsolution at 20° C. per 100 parts of the chips. EVOH chips were dewateredand isolated from the solution and dried for 4 hours in a hot-air drierat 80° C., followed by drying for 16 hours at 100° C. to obtain EVOHchips. The obtained EVOH chips contained 0.11 part of boric acid and0.01 part of sorbic acid per 100 parts of EVOH.

The melt index of this EVOH was 1.6 g/10 minutes (ASTM-D1238, measuredat 190° C., under a load of 2160 g). This EVOH chip is called EVOH (B1).

Manufacturing Example 2

EVOH (B2) containing 0.05 part of p-myrcene per 100 parts of EVOH wasobtained in the same manner as in Manufacturing Example 1 except for theuse of 2 parts of p-myrcene instead of the 2 parts of sorbic acid inManufacturing Example 1 (1) as the conjugated polyene compound (D).

Manufacturing Example 3

EVOH (B3) was obtained in the same manner as in Manufacturing Example 1except that sorbic acid was not added to EVOH water/methanol solution inManufacturing Example 1(1).

Manufacturing Example 4

EVOH (B4) containing 0.002 part of sorbic acid per 100 parts of EVOH wasobtained in the same manner as in Manufacturing Example 1 except forchanging the amount of sorbic acid added to EVOH water/methanol solutionfrom 2 parts to 0.4 part in Manufacturing Example 1(1).

Manufacturing Example 5

EVOH (B5) containing 0.0032 part of sorbic acid per 100 parts of EVOHwas obtained in the same manner as in Manufacturing Example 1 except forchanging the amount of sorbic acid added to EVOH water/methanol solutionfrom 2 parts to 0.65 part in Manufacturing Example 1(1).

Manufacturing Example 6

(1) Porous EVOH chips were obtained in the same manner as inManufacturing Example 1 except that EVOH having an ethylene content of32 mol % and a degree of saponification of 99.8 mol %, and an limitingviscosity [η]_(ph) of 0.112 l/gas measured at 30° C. using a liquidmixture of water/phenol=15/85 (mass ratio) as a solvent.

(2) The porous EVOH chips obtained in (1) above were consecutivelyrinsed with 0.1 mass % aqueous acetic solution and ion exchanged waterin the same manner as in Manufacturing Example 1(2), and then were driedin the same manner as in Manufacturing Example 1(2) without immersing inaqueous boric acid solution. In this way, EVOH (B6) was obtained. Themelt index of this EVOH (ASTM-D1238, measured at 190° C., under a loadof 2160 g) was 1.5 g/10 minutes.

Manufacturing Example 7

40 parts of low density polyethylene {LDPE, melt index 1.5 g/10 minutes(ASTM-D1238, measured at 190° C.), hereinafter simply, “LDPE”}, 2 partsof calcium stearate which is a higher fatty acid metal salt (C), 57.74parts of EVAc (hereinafter simply, “EVAc (E1)”) with vinyl acetate unitsof 7.0 mol % and melt index of 2.7 g/10 minutes (ASTM-D1238, measured at190° C., under a load of 2160 g), and 2.26 parts of a saponifiedethylene-vinyl acetate copolymer (hereinafter, “S-EVOH (F1)”) having anethylene content of 89 mol %, a degree of saponification of vinylacetate units of 97 mol % and melt index of 5.1 g/10 minutes(ASTM-D1238, measured at 190° C., under a load of 2160 g), weredry-blended. The resulting mixture was pelletized after melt-blending ina twin screw co-rotating extruder having a diameter of 30 mm (TEX-30N(trade name), manufactured by Japan Steel Works, Ltd.) at an extrusiontemperature of 200° C. to obtain a master batch (MB1). According to theNMR analysis of this master batch (MB1), the signal strength ratio(Ja:Jb) between the signal Ja deriving from hydrogen atoms bonded to thecarbon atom to which acetoxy group is bonded, and the signal Jb derivingfrom hydrogen atoms bonded to the carbon atom to which hydroxyl group isbonded, was 94.0:6.0.

Manufacturing Example 8

In Manufacturing Example 7, 2 parts of Mg₆Al₂(OH)₁₆CO₃.4H₂O which is ahydrotalcite (G) were further added by dry-blending. The resultingmixture was pelletized in the same manner as in Manufacturing Example 7.Thus, a master batch (MB2) was obtained.

Manufacturing Example 9

The pelletizing was repeated in the same manner as in ManufacturingExample 7 except that EVAc (E1) and S-EVOH (F1) were not added inManufacturing Example 7. Thus, the master batch (MB3) was obtained.

Manufacturing Example 10

The pelletizing was repeated in the same manner as in ManufacturingExample 7 except that calcium stearate was not added in ManufacturingExample 7. Thus, the master batch (MB4) was obtained.

Manufacturing Example 11

The pelletizing was repeated in the same manner as in ManufacturingExample 7 except that 60 parts of EVAc (E1) were used, instead of 57.74parts of EVAc (E1) and 2.26 parts of S-EVOH (F1) in ManufacturingExample 7. Thus, the master batch (MB5) was obtained.

Manufacturing Example 12

The pelletizing was repeated in the same manner as in ManufacturingExample 7 except that 2 parts of magnesium stearate were used as thehigher fatty acid metal salt (C) instead of 2 parts of calcium stearatein Manufacturing Example 7. Thus, the master batch (MB6) was obtained.

Manufacturing Example 13

The pelletizing was repeated in the same manner as in ManufacturingExample 7 except that the added amount of EVAc (E1) was changed from57.74 parts to 13.47 parts, and that of S-EVOH (F1) was changed from2.26 parts to 0.53 part in Manufacturing Example 7. Thus, the masterbatch (MB7) was obtained. According to the NMR analysis of this masterbatch (MB7), the signal strength ratio (Ja:Jb) between the signal Jaderiving from hydrogen atoms bonded to the carbon atom to which acetoxygroup is bonded, and the signal Jb deriving from hydrogen atoms bondedto the carbon atom to which hydroxyl group is bonded, was 94.0:6.0.

Manufacturing Example 14

The pelletizing was repeated in the same manner as in ManufacturingExample 7 on the mixture obtained by dry-blending 2 parts of calciumstearate which is a higher fatty acid metal salt (C), 57.74 parts ofEVAc (E1) and 2.26 parts of S-EVOH (F1) in Manufacturing Example 7.Thus, the master batch (MB8) was obtained. According to the NMR analysisof this master batch (MB8), the signal strength ratio (Ja:Jb) betweenthe signal Ja deriving from hydrogen atoms bonded to the carbon atom towhich acetoxy group is bonded, and the signal Jb deriving from hydrogenatoms bonded to the carbon atom to which hydroxyl group is bonded, was94.0:6.0.

Manufacturing Example 15

The pelletizing was repeated in the same manner as in ManufacturingExample 7 except that 60 parts of S-EVOH (F1) were used instead of 57.74parts of EVAc (E1) and 2.26 parts of S-EVOH (F1) in ManufacturingExample 7. Thus, the master batch (MB9) was obtained.

Example 1

As polyolefin (A), polypropylene {melt index 5.4 g/10 minutes(ASTM-D1238, measured at 230° C.), hereinafter “PP”} was used. 88 partsof the PP, 10 parts of EVOH (B1), and 5.1 parts of the master batch(MB1) were dry-blended to obtain a mixture. The composition of thismixture was 88 parts of PP which is a polyolefin (A), 2 parts of LDPE,10 parts of EVOH (B), 0.1 part of calcium stearate which is a higherfatty acid metal salt (C), 0.001 part of sorbic acid which is aconjugated polyene compound (D), 2.88 parts of EVAc (E1), and 0.12 partof S-EVOH (F1). Using a single screw extruder having a diameter of 20 mm(Laboplastmill—manufactured by Toyo Seiki, Co.) and a 300 mm wide T-dieextruder, a single layer film, 40 μm thick, was manufactured from thismixture. The film manufacturing temperature was 190 to 230° C. at theextruder, and 220° C. at the die. The screw rotation was 40 rpm, and thevolume of discharge was 0.95 kg/hour. About 50 m of the film was sampled1 hour after the mixture was put in the extruder hopper. On the centerpart of the sampled film, a square, 10 cm by 10 cm, was drawn and thenumber of EVOH aggregates, approximately 200 μm or more in diameter (themaximum diameter), in this square was counted using the backlight of atable-top fluorescent lamp. This counting was done at an interval of 20cm, with a total of 100 positions along the length of the sampled film.The average of EVOH aggregate count per 100 cm² was calculated to be0.10 piece.

Example 2

The dry-blended mixture was obtained in the same manner as in Example 1except that 10 parts of EVOH (B2) containing j-myrcene were used insteadof 10 parts of EVOH (B1) containing sorbic acid in Example 1. A singlelayer film was manufactured from this mixture and then the EVOHaggregates in the obtained film were counted in the same manner as inExample 1. The result was 0.12 piece per 100 cm².

Example 3

The dry-blended mixture was obtained in the same manner as in Example 1except that 5.2 parts of the master batch (MB2) containing ahydrotalcite (G) were dry-blended instead of 5.1 parts of themasterbatch (MB1) in Example 1. A single layer film was manufacturedfrom this mixture and then the EVOH aggregates in the obtained film werecounted in the same manner as in Example 1. The result was 0.04 pieceper 100 cm².

Comparative Example 1

In the process of Example 1, 90 parts of PP, and 10 parts of EVOH (B3)not containing conjugated polyene compounds (D) were dry-blended. Asingle layer film was manufactured from this mixture and then the EVOHaggregates in the obtained film were counted in the same manner as inExample 1. The result was 100 pieces or more per 100 cm².

Comparative Example 2

A single layer film was manufactured in the same manner as in Example 1except that 5.0 parts of the master batch (MB4) not containing calciumstearate which is a higher fatty acid metal salt (C) were used, insteadof 5.1 parts of the master batch (MB1) in Example 1. A single layer filmwas manufactured from this mixture and then the EVOH aggregates in theobtained film were counted in the same manner as in Example 1. Theresult was 7.51 pieces per 100 cm².

Comparative Example 3

A single layer film was manufactured in the same manner as in Example 1except that 2.1 parts of the master batch (MB3) not containing EVAc (E1)or S-EVOH (F1) were used instead of 5.1 parts of the master batch (MB1)in Example 1. A single layer film was manufactured from this mixture andthen the EVOH aggregates in the obtained film were counted in the samemanner as in Example 1. The result was 6.12 pieces per 100 cm².

Comparative Example 4

A single layer film was manufactured in the same manner as in Example 1except that 5.1 parts of the master batch (MB5) not containing S-EVOH(F1) were used instead of 5.1 parts of the master batch (MB1) inExample 1. A single layer film was manufactured from this mixture andthen the EVOH aggregates in the obtained film were counted in the samemanner as in Example 1. The result was 4.33 pieces per 100 cm².

Example 4

A single layer film was manufactured in the same manner as in Example 1except that 68 parts of PP; 30 parts of EVOH (B5); and 5.1 parts of themaster batch (MB1) containing calcium stearate which is a higher fattyacid metal salt (C), EVAc (E1), and S-EVOH (F1); were dry-blended inExample 1. A single layer film was manufactured from this mixture andthen the EVOH aggregates in the obtained film were counted in the samemanner as in Example 1. The result was 0.27 piece per 100 cm².

Example 5

A single layer film was manufactured in the same manner as in Example 1except that 10 parts of EVOH (B6) not containing boric acid were used,instead of 10 parts of EVOH (B1) in Example 1. A single layer film wasmanufactured from this mixture and then the EVOH aggregates in theobtained film were counted in the same manner as in Example 1. Theresult was 0.45 piece per 100 cm².

Example 6

A single layer film was manufactured in the same manner as in Example 1except that 5.1 parts of the master batch (MB6) containing magnesiumstearate were used, instead of 5.1 parts of the master batch (MB1) whichcontain calcium stearate in Example 1. A single layer film wasmanufactured from this mixture and then the EVOH aggregates in theobtained film were counted in the same manner as in Example 1. Theresult was 0.13 piece per 100 cm².

Comparative Example 5

A single layer film was manufactured in the same manner as in Example 1except that 10 parts of EVOH (B3) not containing conjugated polyenecompounds (D) were used, instead of 10 parts of EVOH (B1) in Example 1.A single layer film was manufactured from this mixture and then the EVOHaggregates in the obtained film were counted in the same manner as inExample 1. The result was 0.80 piece per 100 cm².

Comparative Example 6

A single layer film was manufactured in the same manner as in Example 1except that 48 parts of PP, 50 parts of EVOH (B4), and 5.1 parts of themaster batch (MB1) were dry-blended in Example 1. A single layer filmwas manufactured from this mixture and then the EVOH aggregates in theobtained film were counted in the same manner as in Example 1. Theresult was 3.54 pieces per 100 cm².

Comparative Example 7

88 parts of PP, 10 parts of EVOH (B1) containing conjugated polyenecompounds (D), and 5.1 parts of the master batch (MB1) were dry-blended,and then further dry-blended with 19.9 parts of calcium stearate. It wasattempted to manufacture a single layer film by using this mixture inthe same manner as in Example 1. However, calcium stearate in liquidform, which had separated from the resins, seeped out of a T-die lippart and many holes were formed on the film surface, and thereforecounting of EVOH aggregates was not possible.

Example 7

A single layer film was manufactured in the same manner as in Example 1except that 2.8 parts of the master batch (MB7) were used, instead of5.1 parts of the master batch (MB1) in Example 1. A single layer filmwas manufactured from this mixture and then the EVOH aggregates in theobtained film were counted in the same manner as in Example 1. Theresult was 0.31 piece per 100 cm².

Example 8

The process of Example 1 was repeated to prepare a dry blend except thatEVOH (B3) not containing conjugated polyene compound (D) was usedinstead of 10 parts of EVOH (B1) in Example 1. To the mixture thusobtained, sorbic acid which is a conjugated polyene compound (D) wasdry-blended by 0.001 part relative to 10 parts of EVOH (B3). By usingthe obtained mixture, a single layer film was manufactured in the samemanner as in Example 1. The results showed the EVOH aggregate count of0.25 piece per 100 cm².

Example 9

A single layer film was manufactured in the same manner as in Example 1except that 88 parts of high density polyethylene {melt index 0.9 g/10minutes (ASTM-D1238, measured at 190° C.) hereinafter, “HDPE” } wereused instead of 88 parts of PP as polyolefin (A) in Example 1. A singlelayer film was manufactured from this mixture and then the EVOHaggregates in the obtained film were counted in the same manner as inExample 1. The result was 0.18 piece per 100 cm².

Comparative Example 8

In the process of Example 1, 88 parts of PP, 10 parts of EVOH (B3) notcontaining conjugated polyene compound (D) and 5.1 parts of the masterbatch (MB1) were dry-blended. To the mixture thus obtained, 5 parts ofsorbic acid which is a conjugated polyene compound (D) were added andfurther dry-blended to prepare a uniform blend. By using this mixture, asingle layer film was manufactured in the same manner as in Example 1.The results showed the EVOH aggregate count of 100 pieces or more per100 cm².

Comparative Example 9

A single layer film was manufactured in the same manner as in Example 9except that 90 parts of HDPE were used and the master batch (MB1) wasnot added in Example 9. A single layer film was manufactured from thismixture and then the EVOH aggregates in the obtained film were countedin the same manner as in Example 1. The result was 4.56 pieces per 100cm².

Example 10

The dry-blended mixture was obtained in the same manner as in Example 1except that 90 parts of PP and 3.1 parts of the master batch (MB8) wereused, instead of 88 parts of PP and 5.1 parts of the master batch (MB1)in Example 1. A single layer film was manufactured from this mixture andthen the EVOH aggregates in the obtained film were counted in the samemanner as in Example 1. The result was 0.11 piece per 100 cm².

Comparative Example 10

A single layer film was manufactured in the same manner as in Example 1except that 5.1 parts of the master batch (MB9) not containing EVAc (E1)were used, instead of 5.1 parts of the master batch (MB1) in Example 1.A single layer film was manufactured from this mixture and then the EVOHaggregates in the obtained film were counted in the same manner as inExample 1. The result was 0.87 piece per 100 cm².

Example 11

Manufacturing testing of co-extrusion film including the resincomposition layers of the present invention was performed by using thefollowing four types of 7-layer co-extrusion cast film manufacturingequipment.

Extruder (1): single screw, screw diameter 65 mm, L/D=22, for outerlayer polyolefin

Extruder (2): single screw, screw diameter 40 mm, L/D=26, for resincomposition of this present invention

Extruder (3): single screw, screw diameter 40 mm, L/D=22, for adhesiveresins

Extruder (4): single screw, screw diameter 40 mm, L/D=26, for EVOH

Co-extrusion film manufacturing was performed by feeding PP intoExtruder (1), a mixture of 88 parts of PP, 10 parts of EVOH (B1), and5.1 parts of the master batch (MB1) prepared by dry-blending in the samemanner as in Example 1, into Extruder (2), a modified polypropyleneadhesive resin modified with maleic acid anhydride (ADMER QF-500(tradename), manufactured by Mitsui Chemical, Inc.) into Extruder (3),and EVOH (B1) into Extruder (4), respectively. The extrusion temperaturewas 200 to 240° C. for Extruder (1), 160 to 220° C. for Extruder (2),160 to 230° C. for Extruder (3), 170 to 210° C. for Extruder (4), and220° C. for feed block and die. The objective for the manufacturedmultilayer film composition and the thickness was: PP/resin compositionof the present invention/adhesive resin/EVOH/adhesive resin/resincomposition of the present invention/PP=30/15/2.5/5/2.5/15/30 μm, atotal of 100 μm in thickness made of four types and seven layers.

According to the observation of the appearance of the film sampling ofthe multilayer film after 2 hours following the initiation of the filmmanufacturing, it was concluded that the obtained multilayer film doesnot present any problem for practical application, with hardly anydeteriorated appearance attributable to EVOH aggregation.

Comparative Example 11

A multi layer film was obtained in the same manner as in Example 11except that the mixture used for feeding the Extruder (2) in Example 11was replaced by the mixture used in Comparative Example 1 prepared bydry-blending 90 parts of PP and 10 parts of EVOH (B3). The obtainedmultilayer film clearly showed a poor appearance due to EVOH aggregatesat a level unsuitable for practical application.

Comparative Example 12

A multilayer film was obtained in the same manner as in Example 11except that the mixture used for feeding the Extruder (2) in Example 11was replaced by the mixture used in Comparative Example 5 prepared bydry-blending 88 parts of PP, 10 parts of EVOH (B3) not containingconjugated polyene compounds (D); and 5.1 parts of the master batch(MB1) containing calcium stearate which is a higher fatty acid metalsalt (C), EVAc (E1), and S-EVOH (F1). Although the appearance of theobtained multilayer film was better than that of the multilayer film ofComparative Example 11, it still showed some poor appearance due to EVOHaggregates at a level unsuitable for practical application.

Comparative Example 13

A multilayer film was obtained in the same manner as in Example 11except that the mixture used for feeding the Extruder (2) in Example 11was replaced by the mixture used in Comparative Example 3 prepared bydry-blending 88 parts of PP, 10 parts of EVOH (B1), and 2.1 parts of themaster batch (MB3) not containing EVAc (E1) or S-EVOH (F1). Although theappearance of the obtained multilayer film was better than that of themultilayer film of Comparative Example 11, it still showed some poorappearance due to EVOH aggregates at a level unsuitable for practicalapplication.

Comparative Example 14

A multilayer film was obtained in the same manner as in Example 11except that the mixture used for feeding the Extruder (2) in Example 11was replaced by the mixture used in Comparative Example 2 prepared bydry-blending 88 parts of PP, 10 parts of EVOH (B1), and 5.0 parts of themaster batch (MB4) not containing higher fatty acid metal salts (C).Although the appearance of the obtained multilayer film was better thanthat of the multilayer film of Comparative Example 11, it still showedsome poor appearance due to EVOH aggregates at a level unsuitable forpractical application.

Example 12

A multilayer film was obtained in the same manner as in Example 11except that the mixture used for feeding the Extruder (2) in Example 11was replaced by the mixture used in Example 3 prepared by dry-blending88 parts of PP, 10 parts of EVOH (B1), and 5.2 parts of the master batch(MB2) containing a hydrotalcite (G). The appearance of the obtainedmultilayer film was even better than that of the multilayer film ofExample 11, with no poor appearance due to EVOH aggregates.

The results of each Example and Comparative Example are summarized inTable 1 and Table 2.

TABLE 1 Higher fatty acid metal salt Polyolefin (A) EVOH (B) (C) TypeAmount Type Amount Type Amount Type Amount¹⁾ EX. 1 PP 88 LDPE 2 EVOH(B1)10 Calcium stearate 0.1 EX. 2 PP 88 LDPE 2 EVOH(B2) 10 Calcium stearate0.1 EX. 3 PP 88 LDPE 2 EVOH(B1) 10 Calcium stearate 0.1 EX. 4 PP 68 LDPE2 EVOH(B5) 30 Calcium stearate 0.1 EX. 5 PP 88 LDPE 2 EVOH(B6) 10Calcium stearate 0.1 EX. 6 PP 88 LDPE 2 EVOH(B1) 10 Magnesium stearate0.1 EX. 7 PP 88 LDPE 2 EVOH(B1) 10 Calcium stearate 0.1 EX. 8 PP 88 LDPE2 EVOH(B3) 10 Calcium stearate 0.1 EX. 9 HDPE 88 LDPE 2 EVOH(B1) 10Calcium stearate 0.1 EX. 10 PP 90 EVOH(B1) 10 Calcium stearate 0.1Comparative EX. 1 PP 90 EVOH(B3) 10 — — Comparative EX. 2 PP 88 LDPE 2EVOH(B1) 10 — — Comparative EX. 3 PP 88 LDPE 2 EVOH(B1) 10 Calciumstearate 0.1 Comparative EX. 4 PP 88 LDPE 2 EVOH(B1) 10 Calcium stearate0.1 Comparative EX. 5 PP 88 LDPE 2 EVOH(B3) 10 Calcium stearate 0.1Comparative EX. 6 PP 48 LDPE 2 EVOH(B4) 50 Calcium stearate 0.1Comparative EX. 7 PP 88 LDPE 2 EVOH(B1) 10 Calcium stearate 20  Comparative EX. 8 PP 88 LDPE 2 EVOH(B3) 10 Calcium stearate 0.1Comparative EX. 9 HDPE 90 EVOH(B1) 10 — — Comparative EX. 10 PP 88 LDPE2 EVOH(B1) 10 Calcium stearate 0.1 NMR EVOH Conjugated polyene EVAcS-EVOH Hydrotalcite strength aggregate compound (D) (E) (F) (G) ratiocount Type Amount¹⁾ Amount¹⁾ Amount¹⁾ Amount¹⁾ Ja:Jb (per 100 cm²) EX. 1sorbic acid 0.001 2.88 0.12 94.0:6.0 0.10 EX. 2 β-myrcene 0.005 2.880.12 94.0:6.0 0.12 EX. 3 sorbic acid 0.001 2.88 0.12 0.1²⁾ 94.0:6.0 0.04EX. 4 sorbic acid 0.00096 2.88 0.12 94.0:6.0 0.27 EX. 5 sorbic acid0.001 2.88 0.12 94.0:6.0 0.45 EX. 6 sorbic acid 0.001 2.88 0.12 94.0:6.00.13 EX. 7 sorbic acid 0.001 0.672  0.028 94.0:6.0 0.31 EX. 8 sorbicacid 0.001 2.88 0.12 94.0:6.0 0.25 EX. 9 sorbic acid 0.001 2.88 0.1294.0:6.0 0.18 EX. 10 sorbic acid 0.001 2.88 0.12 94.0:6.0 0.11Comparative EX. 1 — — — — — >100 Comparative EX. 2 sorbic acid 0.0012.88 0.12 94.0:6.0 7.51 Comparative EX. 3 sorbic acid 0.001 — — — 6.12Comparative EX. 4 sorbic acid 0.001 3 — 100.0 4.33 Comparative EX. 5 — —2.88 0.12 94.0:6.0 0.80 Comparative EX. 6 sorbic acid 0.001 2.88 0.1294.0:6.0 3.54 Comparative EX. 7 sorbic acid 0.001 2.88 0.12 94.0:6.0 —³⁾Comparative EX. 8 sorbic acid 5 2.88 0.12 94.0:6.0 >100 Comparative EX.9 sorbic acid 0.001 — — — 4.56 Comparative EX. 10 sorbic acid 0.001 — 3 3.0:97.0 0.82 ¹⁾Parts by mass per 100 parts by mass of the total of thepolyolefin (A) and the EVOH (B) ²⁾Hydrotalcite: Mg₆Al₂(OH)₁₆CO₃•4H₂O³⁾Film manufacture was impossible due to foaming

TABLE 2 Higher fatty acid Polyolefin (A) EVOH (B) metal salt (C) TypeAmount Type Amount Type Amount Type Amount¹⁾ EX. 11 PP 88 LDPE 2EVOH(B1) 10 Calcium 0.1 stearate EX. 12 PP 88 LDPE 2 EVOH(B1) 10 Calcium0.1 stearate Comparative EX. 11 PP 90 EVOH(B3) 10 — — Comparative EX. 12PP 88 LDPE 2 EVOH(B3) 10 Calcium 0.1 stearate Comparative EX. 13 PP 88LDPE 2 EVOH(B1) 10 Calcium 0.1 stearate Comparative EX. 14 PP 88 LDPE 2EVOH(B1) 10 — — Conjugated NMR polyene EVAc S-EVOH Hydrotalcite strengthcompound (D) (E) (F) (G) ratio Film surface Type Amount¹⁾ Amount¹⁾Amount¹⁾ Amount¹⁾ Ja:Jb appearance³⁾ EX. 11 sorbic 0.001 2.88 0.1294.0:6.0 B acid EX. 12 sorbic 0.001 2.88 0.12 0.1²⁾ 94.0:6.0 A acidComparative EX. 11 — — — — D Comparative EX. 12 — — 2.88 0.12 94.0:6.0 CComparative EX. 13 sorbic 0.001 — — C Comparative EX. 14 sorbic 0.0012.88 0.12 94.0:6.0 C acid ¹⁾Parts by mass per 100 parts by mass of thetotal of the polyolefin (A) and the EVOH (B) ²⁾Hydrotalcite:Mg₆Al₂(OH)₁₆CO₃•4H₂O ³⁾A: No appearance anomalies were found. B:Appearance anomalies were substantially not found, hence practicallyacceptable. C: Some appearance anomalies were found, hence practicallyproblematic. D: Appearance anomalies were clearly found, hencepractically problematic.

The present invention relates to a resin composition comprising;polyolefin (A); EVOH (B); higher fatty acid metal salt (C) having 8 to22 carbon atoms; conjugated polyene compound (D) having a boiling pointof 20° C. or higher; EVAc (E); and S-EVOH (F), wherein the mass ratio(A:B) of polyolefin (A) and EVOH (B) is 60:40 to 99.9:0.1, the amount ofhigher fatty acid metal salts (C) is in the range of 0.0001 to 10 partsby mass per 100 parts by mass of the total of polyolefin (A) and EVOH(B), the amount of conjugated polyene compound (D) is in the range of0.000001 to 1 part by mass per 100 parts by mass of the total ofpolyolefin (A) and EVOH (B), and the total amount of EVAc (E) andsaponified ethylene-vinyl acetate copolymer (F) is 0.3 part by mass ormore per 100 parts by mass of the total of polyolefin (A) and EVOH (B).By using this composition, a poor appearance caused by the EVOHaggregation and flow anomalies attributable to the aggregation can beprevented, and molded articles having an excellent appearance can beobtained.

The invention claimed is:
 1. A method for producing a resin compositioncomprising preparing a master batch by melt-blending a higher fatty acidmetal salt (C) having 8 to 22 carbon atoms, a random copolymer (E)consisting of ethylene and vinyl acetate units, and a saponifiedethylene-vinyl acetate copolymer (F) having an ethylene content of 70 to94 mol % and having a degree of saponification of vinyl acetate units of40% or more, melt-blending the master batch, a polyolefin (A), asaponified ethylene-vinyl acetate copolymer (B) having an ethylenecontent of 20 to 65 mol % and having a degree of saponification of vinylacetate units of 96% or more, and a conjugated polyene compound (D)having a boiling point of 20° or higher, wherein a mass ratio (A:B) ofthe polyolefin (A) and the saponified ethylene-vinyl acetate copolymer(B) is 60:40 to 99.9:0.1, an amount of the higher fatty acid metal salts(C) is in the range of 0.0001 to 10 parts by mass per 100 parts by massof the total of the polyolefin (A) and the saponified ethylene-vinylacetate copolymer (B), an amount of conjugated polyene compound (D) isin the range of 0.000001 to 1 part by mass per 100 parts by mass of thetotal of the polyolefin (A) and the saponified ethylene-vinyl acetatecopolymer (B), and a total amount of the ethylene-vinyl acetatecopolymer (E) and the saponified ethylene-vinyl acetate copolymer (F) is0.3 part by mass or more per 100 parts by mass of the total of thepolyolefin (A) and the saponified ethylene-vinyl acetate copolymer (B).2. The method of claim 1, wherein the polyolefin (A) and the saponifiedethylene-vinyl acetate copolymer (B) are obtained from scraps of layeredproducts having the polyolefin (A) layer and the saponifiedethylene-vinyl acetate copolymer (B) layer.
 3. The method of claim 1,wherein a mass ratio (E:F) of the random copolymer (E) and thesaponified ethylene-vinyl acetate copolymer (F) is 99.9:0.1 to70.0:30.0.
 4. The method of claim 1, wherein the master batch furthercomprises the polyolefin (A).
 5. The method of claim 1, wherein themaster batch analyzed by nuclear magnetic resonance spectroscopy(¹H-NMR) method shows a signal strength ratio (Ja:Jb) of a signal Jaderiving from hydrogen atoms bonded to carbon atoms to which acetoxygroups are bonded, and a signal Jb deriving from hydrogen atoms bondedto carbon atoms to which hydroxyl groups are bonded, in the range of99.5:0.5 to 70.0:30.0.
 6. The method of claim 1, wherein the masterbatch further comprises a hydrotalcite (G), wherein the resincomposition contains 0.0001 to 10 parts by mass hydrotalcite (G) per 100parts by mass of the total of the polyolefin (A) and the saponifiedethylene-vinyl acetate copolymer (B).
 7. A method for producing amultilayer structure comprising co-extrusion molding, at least, theresin composition produced by the method of claim 1 and a saponifiedethylene-vinyl acetate copolymer having an ethylene content of 20 to 65mol % and having a degree of saponification of the vinyl acetate unitsof 96% or more, wherein the multilayer structure comprises at least alayer made of the resin composition and a layer made of the saponifiedethylene-vinyl acetate copolymer.